1. Technical Field
This invention relates to cargo restraints for securing a cargo container or pallet and, more particularly, to an improved cargo restraint device that minimizes inadvertent disengagement thereof and a method of using the same.
2. Background Art
As is well known in the art, cargo restraints are commonly used in aircraft and other vehicles to secure cargo containers or pallets to prevent excessive movement during transport. Typically, cargo containers are loaded, handled, and aligned into their approximate position within the compartment of the aircraft. As the cargo container is positioned into its final position, a retractable cargo restraint is lifted from a position within the floor into an engaged and locked position. The cargo restraint overlaps a flange-like portion or pocket of the cargo container and secures the cargo container relative to the floor to minimize vertical and horizontal movement thereof.
As described in detail in U.S. Pat. No. 3,796,397, which is incorporated herein by reference, a cargo restraint is shown having a frame secured within a track formed in the aircraft floor. The frame may include rollers for guiding a pallet or container thereover. The cargo restraint further includes a pair of rotatable latch arms or pawls, which are moveable between an erect, operative position and a collapsed position. In the erect, operative position, the first of the pair of pawls is engaged with a pallet or container. In the collapsed position, the first and second pawls lie within the frame and below the upper surface of the rollers to enable free movement of the containers or pallets. Typically, one or more cargo restraints is provided at opposite ends of the container to minimize movement of the container during acceleration and deceleration of the aircraft or other vehicle.
In operation, conventional cargo restraints are released from their erect, operative position to their collapsed position by depressing the inner pawl. This depression of the inner pawl releases the inner pawl from the outer pawl thereby enabling the outer pawl to pivot and disengage from the container under the force of a spring. The pawls are then allowed to pivot to the collapsed position to enable the container to be moved freely on the rollers. However, in known designs the cargo restraints may become inadvertently disengaged from the container due to vibration or external impact applied to the pawls. Attempts have been made to overcome this problem by adding various additional locking features, such as retractable pins, to prevent rotation of the pawls. For example, U.S. Pat. No. 4,121,789, which is incorporated by reference herein, illustrates such a locking pin design. However, this adds to the cost, complexity, and difficulty in operating the cargo restraint. Additionally, it is now believed that under extreme force, such as 13,000 lbs., these pins may shear and consequently fail to secure the cargo container. Moreover, this particular prior art design further requires unlocking of the pins by hand to unlatch the pawl from the cargo container. Accordingly, there exists a need in the relevant art to provide a cargo restraint device that is capable of preventing inadvertent disengagement caused by vibration or external impacts without adding additional parts.
It should be appreciated that the less time it takes to prepare an aircraft for departure, the more profitable that aircraft will become. Thus, time saved during operations, such as cargo handling, continue to be of utmost importance. Therefore, quickness, ease, and simplicity of the cargo handling equipment, such as the cargo restraints, are needed. Generally, a cargo restraint device that is capable of being unlocked by foot pressure is preferred as this method would enable a worker to quickly unlock and move the container without having to reach down and unlock a large container by hand. This method of unlocking the cargo restraint by foot pressure would further enable the worker to steady the container during the unlocking process. Accordingly, there exists a need in the relevant art to provide a cargo restraint device that is capable of being quickly disengaged by foot pressure, which does not inadvertently disengage due to vibration or external impact.
Accordingly, it is a principal object of the present invention to provide a cargo restraint device that can reliably secure a cargo container or pallet within an aircraft or vehicle.
It is another object of the present invention to provide a cargo restraint device that can reliably resist vibration or external impact to prevent inadvertent disengagement of the cargo restraint device from the cargo container or pallet.
It is another object of the present invention to provide a cargo restraint device that can be actuated by foot pressure without the need to manually unlatch the cargo restraint device by hand.
It is still another object of the present invention to provide a cargo restraint device that does not require complicated locking features that require additional parts and/or components.
It is yet another object of the present invention to provide a cargo restraint device that is not susceptible to the shortcomings of the prior art designs.
The above and other objects are provided by a cargo restraint device in accordance with preferred embodiments of the present invention. The cargo restraint device of the present invention employs a pair of cooperating surfaces on the pawls that provide a locking engagement that is resistant to vibration and external impact. However, this pair of cooperating surfaces on the pawls may be easily and conveniently disengaged by properly positioned foot pressure. The cargo restraint device of the present invention achieves these results without the need for additional parts and/or components as required by the prior art method.
The cargo restraint device of the present invention includes a base having an outer pawl and an inner pawl pivotally connected to the base. The outer pawl includes a generally horizontal locking surface that cooperates with a generally horizontal locking surface on the inner pawl to provide a cargo restraint device capable of resisting vibration and downward forces applied to the inner pawl to prevent inadvertent disengagement of the cargo restraint device.
The cargo restraint device of the present invention is unlatched by applying generally downward foot pressure upon the outer pawl to enable the inner pawl to rotate to an unlocked position. The foot pressure is then released from the outer pawl to enable the outer pawl and inner pawl to rotate to an unlatched position.